A power amplifier providing greater than ten (10) Watts of power requires a relatively high primary voltage to enable an efficient radio frequency transmission. On the other hand, transistors included in a circuit, which provide a digital waveform for modulating an RF signal for transmission, require low operating voltages, such as one (1) to two (2) volts. These transistors are typically susceptible to a low voltage breakdown and, generally, need protection from high voltages that may be reflected from the output side of a power amplifier. Impedance mismatches between the output side of a power amplifier and its load (such as an antenna) may produce a high voltage standing wave ratio (VSWR) that forms a voltage likely to exceed the safe operating margins of the transistors generating the digital waveform.
Due to operating voltage differences, separate circuits are typically required between a circuit used for generation of signal waveforms and a circuit used for generation of RF power. Hence, the need for separate digital waveform generators and RF power amplifiers.
Conventional circuits using complimentary metal-oxide-semiconductor (CMOS) fabrication techniques cannot synthesize a digital waveform directly at an antenna for transmission at high RF power levels. The elimination of the entire RF signal generation and power amplification chain is not possible with conventional circuits. The present invention includes a composite device that may be used for direct synthesis of a digital waveform at an antenna, which eliminates the need for an RF signal generator and power amplifier chain.